Gael v



N ED STATES PATENT OFFICE.

CARL V. PETRAEUS, OF J OPLIN, MISSOURI, ASSIGNOR TO OLIVER II. PICHER, OF SAME PLACE.

LEAD PIGMENT'AND METHOD OF MANUFACTURING SAME.

SPECIFICATION forming part of Letters Patent No. 611,389, dated September 27, 1898.

Application filed March 23 1896. Serial No. 584,520. (No specimens.)

from lead; and particularly it relates to the manufacture of sublimed lead salts and compounds for use as a pigment.

Heretofore ores or other material containing lead and sulfur have been treated in furnaces of various constructions, with the result of sublimin g or driving 0% as a fume a greater or less percentage of the metal present. This fume is of varying composition, in accordance with the treatment to which the metalbearing material has been subjected. In some cases it consists of lead sulfid and lead sulfate, both in considerable proportion, and some sublimed oxid of lead, While in other treatments it is essentially' a sulfate of lead substantiallyfree from lead sulfid, but mixed, as before, with some sublimed lead oxid. A small percentage of lead sulfite is also sometimes found in the fume, and it is rather the rule that such sublimed fumes should be mixed with fumes of other metals, notably zinc. For many years past these sublimed fumes have been used as the base of a pigment. In such cases the lead sulfite and lead sulfid, if present, are oxidized to the condition of a sulfate, and in this condition the material is generally known by the name of sublimed white lead. The sublimed fume containing lead sulfid has also been used as a pigment basis; but it is dark in color and has as yet not come into general use.

While the lead fumes of the character above described have been and are successfully used in the manufacture of paints, they are as a rule used in admixture with otherpigments, and one reason for this is that the sublimed fumes, particularly in the form of sublimed able for certain classes of work to which the ordinary commercial white lead is applied. Particularly I would note that the sublimed lead pigment has when applied a glossy appearance, which for some purposes is undesirable, and also that it does not lend itself to stencil-work.

In another application filed simultaneously herewith-to wit, March 23, 1896and bearing the serial number 584,519 I have described my discovery and invention by which I overcome the defects in the sublimed pigment, which I have briefly noted above, and impart to it a character which more nearly assimilates it for use as a pigment t0 the ordinary white lead or lead carbonate, while at the same time preserving its distinctive parts as compared with the said ordinary white lead, my said invention being based upon my discovery that the sublimed lead pigment when the lead and sulfur compounds are chiefly in the form of lead sulfate will be increased in density and at the same time so changed in character as to make a paint which will have a flat finish and a paint which can be used for stencil-work and like purpose by subjecting it to a cintering treatment and then grinding the cintered productto proper consistency for a pigment basis. The temperature employed for the cintering of the fume should be, as stated in my said contemporaneous application, one which will cause a coalescence of the particles of fume, but not sufiiciently high to cause a fusion of the mass. Thus, for instance, I have obtained excellent results at a temperature of about 1,000 Fahrenheit, and I have ascertained that the temperature can be carried close to 2,000 Fahrenheit without causing the fusion of the mass and with the result of cintering the particles together, the best results having been secured by me by the use of a temperature between 1,000 and l,500 Fahrenheit. As stated in my said former application, I have in practice used the Scotch-hearth furnace in which to smelt the ores and compounds containing lead and sulfur, collecting the fumes driven off from the furnace, which consists of a mixture of lead sulfid, lead sulfate, and oxid of lead, in screens, and I have then subjected the fumes collected from the Scotch-hearth furnace to the action of a low-cupola blast-furnace, collecting the fume from the low-cupola furnace, which is essentially a mixture of lead sulfate and lead oxid, and subjecting this material to the cintering treatment aforesaid. It will be understood, however, that any furnace treatment which will produce a lead sublimate containing sulfur and in which the lead and sulfur compounds are chiefly in the form of lead sulfate may be used to produce the sublimed white lead, which I subject to the cintering treatment aforesaid. As is also set forth in my contemporaneous application, the cintered fume resulting from my treatment must in all cases be ground before it is fit for actual use as a pigment, because the result of the treatment is to convert it as a whole into a gritty mass.

My present invention is based on my discovery that the quality as well as the character of the sublimed and cintered lead fume can be much improved by subjecting the material after grinding to the action of a solution of sulfuric acid for the purpose of converting the lead oxid present into lead sulfate and producing a pigment basis consisting, essentially, of sublimed and cintered lead sulfate in admixture with chemicallyprepared lead sulfate, the new compound possessing peculiarities and being adapted 1. In the manufacture of a lead pigment the method which consists in treating material containing lead and sulfur in a furnace adapted to drive off some or all of the lead in the form of a fume made up of lead in combination with sulfur and with oxygen and in which the lead and sulfur compounds are chiefly in the form of lead sulfate, then collecting said fume by screening, then cintering the lead fume to cause the particles of lead sublimate to coalesce but without fusing the mass, then grinding the cintered sublimate and then treating the ground mass with a sulfuric-acid solution to convert the lead oxid contained in it into lead sulfate.

2. As a new article of manufacture a compound consisting essentially of sublimed and cintered lead sulfate in admixture with lead sulfate made from sublimed lead oxid.

CARL V. PETRAEUS.

WVitnesses:

CHARLES F. ZIEGLER, FRANCIS T. CHAMBERS. 

